It is now recommended practice to administer pneumocystis carrinii pneumonia (PCP) prophylaxis to all HIV infected children considered to be at high risk for (PCP). The drug of first choice is trimetroprim- sulfamethoxazole (TMP SMX). The purpose of this study is to compare 2 doses of dapsone for prevention against PCP in HIV infected infants and children who can't tolerate (TMP SMX) . The primary objective of the study are to compare the toxicity of daily versus weekly dapsone for PCP prophylaxis, and to collect study information.